Thermostat using the heat anticipation heater as a part of the mechanical connection between the temperature responsive element and switch operating member

ABSTRACT

A thermostat having a temperature responsive means for providing a mechanical output force to operate a switch wherein a heater means, for providing heat to a thermostat for heat anticipation, provides the mechanical connection between the temperature responsive means and the switch whereby the thermal connection between the heater means and the temperature responsive means remains the same throughout the operation of the thermostat.

United States Patent Kautz 1 1 Jul 25 1972 [54] THERMOSTAT USING THE HEAT 3,277,260 10/1966 Anderson ..337/377 X ANTICIPATION HEATER AS A PART 2,748,223 5/1956 Frank ..337/l00 OF THE MECHANICAL CONNECTION 2,520,906 9/1950 Cade ..337/l07 TCH FOREIGN PATENTS 0R APPLICATIONS OPERATING MEMBER 1,016,320 1/1966 Great Britain ..337/377 [72] Inventor: Murrell F. Kautz, Minneapolis, Minn. Primary Examiner-Bernard lh ny Assistant ExaminerDewitt M. Morgan [73] Assignee: Honeywell Inc., Minneapolis, Minn. Anomey l amom Koontz and Clyde C. Bun [22] Filed: June 1, 1971 ABSTRA T 57 C [21] Appl. No: 148,362 1 A thermostat having a temperature responsive means for providing a mechanical output force to operate a switch [5 2] Cl 3; wherein a heater means, for providing heat to a thermostat for fig /77 107 4 heat anticipation, provides the mechanical connection 1 o between the temperature responsive means and the switch 56 Ref re es Cited whereby the thermal connection between the heater means 1 e c and the temperature responsive means remains the same UNITED STATES PATENTS throughout the operation of the thermostat. 3,463,008 8/1969 Teichert et al. .337/l00 UX 8 Claims, 4 Drawing Figures 2| v 3 3 3| i Q PATENTEBJUL 25 1972 INVENTOR.

MURRELL F. KAUTZ FIG. 2

FIG. I

A TTOR/VE Y.

THERMOSTAT USING THE HEAT ANTICIPATION HEATER AS A PART OF THE MECHANICAL CONNECTION BETWEEN THE TEMPERATURE RESPONSIVE ELEMENT AND SWITCH OPERATING MEMBER BACKGROUND AND SUMMARY OF THE INVENTION In thermostats wherein a temperature responsive element such as a bimetal operates a switch for controlling heating and/or cooling apparatus, the use of an electrical heater to artificially heat the temperature responsive means for heat anticipation purposes is broadly old. Many schemes have been devised for making the thermal connection or heat conducting path between the heater and the temperature responsive means as low as possible. For example in the V. R. Anderson US. Pat. No. 3,277,260, the heater is mounted adjacent the bimetal in a cavity in the base which projects close to the bimetal. In the R. A. Alcott US. Pat. No. 2,993,969 a portion of the sensing element is extended to be near the heat source. In the H. W. Scott US. Pat. No. 3,098,138, the bimetal is used as the heater. In the W. E. Edelman et a]. US. Pat. No. 3,284,002, the heater is mounted in a resilient holder engaging the end of the support shaft for the main bimetal. In the C. L. Nelson US. Pat. No. 3,3l6,374, the heater is mounted on a card attached to the support shaft for the bimetal.

In a thermostat where the bimetal moves so that the air space between the heater and bimetal changes with different positions of the bimetal, the heat transfer path changes which effects the operation of the thermostat. When the heater is mounted directly on the bimetal, a load is imposed on the bimetal which can have some affect upon its mechanical output.

In the present invention the electrical heater providing heat to the temperature responsive means for heat anticipation is used as a part of or the mechanical connection between the temperature responsive means and the switch operating member. The electrical heater is always in close thermal contact with the temperature responsive means or bimetal regardless of the position of the bimetal to provide a thermal connection between the heater and the bimetal which remains unchanged throughout the operation of the thermostat.

FIG. I is a front view of the thermostat showing the bimetal and base with the support for the heat anticipation heater;

FIG. 2 is a side view of the thermostat showing the U-shaped lever supporting the heater between the bimetal and switch operating pin;

FIG. 3 is an enlarged view of the heater configuration; and

FIG. 4 is an enlarged view of another embodiment of the heater configuration.

DESCRIPTION OF THE INVENTION Referring to FIG. I a thermostat has a base member and a cover 16. A temperature responsive element or bimetal II is pivotally supported on base 10 at one end thereof and adjusted at the other end by a knob 12 having a cam surface. Bimetal II engages a switching operating pin or mechanical input 13 for operating a switch 14 for controlling an electrical load such as heating and/or cooling apparatus. The details of the thermostat are more explicitly shown in the Vincent R. Anderson US Pat. No. 3,277,260 as the present application is concerned with an improvement to the thermostat of the Anderson patent.

A heat anticipation heater or electrical resistor heater element 20 is supported in a U-shaped carrier or lever member 21 which is captivated or pivoted at its ends 22 and 23 on base 10. Heater 20 is held between the mechanical output surface or underside of bimetal 11 and pin 13 as shown in FIGS. 2 and 3 whereby upon movement of the bimetal to left or right as the thermostat changes temperature, pin I3 is moved to operate the switch. Carrier 21 is resiliently connected to base 10 by springs 30 which also provide the electrical connection for the heater 20 through the conductors 31 extending through the legs of carrier 21.

Specifically, as shown in FIG. 3, carrier 21 has a pair of projections 32 which extend into holes 33 in base 10 whereby carrier 21 is held against the force of springs 30 by a pair of projections 34 extending in the opposite direction to engage bimetal 11. When heater 20 is connected into the thennostat circuit whether it be as a series connected heater of a parallel connected voltage type" heater, the thermal conducting path for the heat from heater 20 to the bimetal remains unchanged throughout the operation of the thermostat. As bimetal bends to push the operating pin 13 of the switch to the left or right as shown in FIGS. 2 and 3, the contact or engagement with heater 20 remains substantially the same. As carrier 21 is held against bimetal II at projections 34 and at heater 20 by the thrust of the two springs 30 and the thrust of the switch operating pin 13, the carrier follows the movement of the bimetal II at all temperatures to maintain heater 20 in a most efficient contact with bimetal.

To increase the conductivity of the heat from heater 20 to bimetal II, as well as, to cut down the mechanical friction, heat conductive grease 40 is placed between heater 20 on lever 21 and bimetal l l. The carrier 21 provides for shielding of conductors 3! and resistor 20 to prevent hazardous contact in the semi-open thermostat compartment of bimetal II. The resistor 20, and even the conductors 31 if desired, can be potted with a suitable compound 42 to achieve additional insulation and/or to hold the resistor and conductors in place in the carrier 21. 7

Another embodiment of carrier 2] is shown in FIG. 4. Resistor 20 is mounted in a hole in carrier 21 to engage bimetal II for a more efficient thermal contact. Resistor 20 directly contacts bimetal II and pin 13 by having the thrust of pin 13 applied to bimetal I] through resistor 20. Resistor 20 is The embodiments of the invention in which an exclusive property or right is claimed are defined as follows:

1. A thermostat comprising a base member,

temperature responsive means connected to said base member and having a surface providing a mechanical output force,

a heater means for providing artificial heat to said temperature responsive means,

switch means having a mechanical input means, and

mechanical connection means including said heater means for operably connecting said surface providing said mechanical output force to said mechanical input means of said switch means whereby heat from said heater means is conducted through said connection means to said temperature responsive means.

2. The invention of claim 1 wherein,

said temperature responsive means is a bimetal element pivotally supported at one end thereof to said base member and the position of the other end thereof adjusted by a cam whereby said mechanical output is provided at a center portion of said bimetal,

said heater means is an electrical resistor supported by a lever arm pivotally connected to said base,

said mechanical input means of said switch means has a switch operating pin for operating a switch when said pin is moved inward, and

said resistor is held by said lever arm between said center portion of said bimetal and said pin to allow said resistor to have full freedom to move with said bimetal whereby a heat conducting path between said heater means and said temperature responsive means remains unchanged.

3. The invention of claim 2 wherein said lever is a U-shaped member and the free ends of said member are pivotally con nected to said base member by resilient members.

4. The invention of claim 3 wherein said resilient members provide electrical connections for said heater means.

5. The invention of claim 3 wherein said U-shaped member is biased by said resilient members at said free ends against said bimetal.

suitably potted to be held in place in carrier 21 by compound 42. 35

means supporting said heater means as an operable connection between said surface providing said mechanical output force and said mechanical input means of said switch means.=

8. The invention of claim 7 wherein,

said temperature responsive means is a bimetal element pivotally supported on said base member,

said heater means is an electrical resistor supported by a carrier captivated to said base,

said resistor is held to engage said bimetal and said mechanical input whereby the heat conducting path between said heater means and said temperature responsive means remains unchanged throughout the operation of said thermostat.

i k I i 

1. A thermostat comprising a base member, temperature responsive means connected to said base member and having a surface providing a mechanical output force, a heater means for providing artificial heat to said temperature responsive means, switch means having a mechanical input means, and mechanical connection means including said heater means for operably connecting said surface providing said mechanical output force to said mechanical input means of said switch means whereby heat from said heater means is conducted through said connection means to said temperature responsive means.
 2. The invention of claim 1 wherein, said temperature responsive means is a bimetal element pivotally supported at one end thereof to said base member and the position of the other end thereof adjusted by a cam whereby said mechanical output is provided at a center portion of said bimetal, said heater means is an electrical resistor supported by a lever arm pivotally connected to saiD base, said mechanical input means of said switch means has a switch operating pin for operating a switch when said pin is moved inward, and said resistor is held by said lever arm between said center portion of said bimetal and said pin to allow said resistor to have full freedom to move with said bimetal whereby a heat conducting path between said heater means and said temperature responsive means remains unchanged.
 3. The invention of claim 2 wherein said lever is a U-shaped member and the free ends of said member are pivotally connected to said base member by resilient members.
 4. The invention of claim 3 wherein said resilient members provide electrical connections for said heater means.
 5. The invention of claim 3 wherein said U-shaped member is biased by said resilient members at said free ends against said bimetal.
 6. The invention of claim 1 wherein said heater means is supported on said base member to follow the movement of said output surface of said temperature responsive means whereby a heat conducting path between said heater and said temperature responsive means remains the same throughout the operation of the thermostat.
 7. A thermostat comprising a base member, temperature responsive means connected to said base member and having a surface providing a mechanical output force, a heater means providing artificial heat to said temperature responsive means, switch means having a mechanical input means, and means supporting said heater means as an operable connection between said surface providing said mechanical output force and said mechanical input means of said switch means.
 8. The invention of claim 7 wherein, said temperature responsive means is a bimetal element pivotally supported on said base member, said heater means is an electrical resistor supported by a carrier captivated to said base, said resistor is held to engage said bimetal and said mechanical input whereby the heat conducting path between said heater means and said temperature responsive means remains unchanged throughout the operation of said thermostat. 